Quake3World

how do you make it so that you dont get hurt by lave, slime, drowning and all that stuff

The only mod that ever really came close to almost covering some of that was the Corkscrew mod.., and since on your other topic to where you were wondering on how to get unlimited ammo on the railgun..I figure you'll like it since it's an instagib mod.

Download page

Or you could just use cheats:
/god
you can't die.
Dunno cheat for unlimited ammo yet though.
Do you know how to enable those? Cheats that is.